The invention relates to oil lamps for use in esthetic illumination, and more particularly, to an oil lamp of the type having a large oil vessel for extending the burning cycle of the lamp and a molded interference ring for securing the vessel to a base sleeve.
In the field of illumination design, burning oil lamps have been known for centuries. In past agrarian societies, farm lamps and table lamps incorporated an oil vessel within the construction of the lamp. Therefore, the burning oil medium was deposited directly into the oil vessel within the lamp as by pouring. This method resulted in an untidy and dangerous task often creating a fire hazard, which was unsatisfactory.
A later generation of oil burning lamps incorporated a disposable cartridge or vessel which generally eliminated the untidy and hazardous task of replenishing the spent oil in the vessel of the lamp. Many designs of the oil burning lamp which incorporated the disposable cartridge employed a chimney having a maximum diameter of about three inches. Therefore, the disposable cartridge which was fitted into the oil vessel of the lamp was required to be small to fit through the narrow chimney since this generation of lamps normally had a closed bottom surface. Because the disposable cartridge was relatively small, the oil lamp exhibited a short burning cycle.
In keeping with this design, later generations of oil burning lamps were fabricated for accommodating an oil vessel which was also inserted through the chimney. Because the chimney normally was limited to a relatively small diameter, the oil vessel was limited in size. Because the chimney seated in the lamp base, the diameter of the chimney limited the size of the oil vessel that could be placed into the lamp through the chimney. Further, in situations where the chimney was removable from the base of the lamp, a large oil vessel would still interfere with the proper fitting between the chimney and the base of the lamp. Since the bottom of the base for this generation of lamps was normally sealed for supporting the oil vessel, a larger oil vessel could not be inserted into the lamp from the bottom of the base.
In more recent designs, oil burning lamps have been comprised of an oil vessel which was inserted into an outer sleeve which was intended to secure the vessel and to support a chimney which expended the residue of the spent oil and served to transmit the light from the burning flame. Both the oil vessel and the sleeve were comprised of metal. This design was generally unsuccessful because although the engineering tolerances between the metal sleeve and vessel were achievable, the end product produced in mass production did not operate properly.
More current designs of the structure of oil lamps employing a removable oil vessel resulted in the size of the oil vessel being designed so that the sleeve slides over the vessel. One of the major problems associated with this design was that if the vessel is not properly secured within the sleeve, the impulse was to design a larger oil vessel for grasping the inner surface of the base sleeve. However, this design was also unsuccessful because when the outer diameter of the oil vessel was increased to interface with the inner diameter of the base sleeve, too much of the outer surface of the oil vessel contacted the inner surface of the base sleeve. This situation created too much braking surface so that it was very difficult to insert the oil vessel into and remove the oil vessel from the base sleeve.
In more current generations of the vessel-sleeve design of oil burning lamps, high strength molded plastics have been employed. However, the practical aspects of employing engineering molds for such an application do not permit the tolerances to be so exact as to cause the base sleeve and oil vessel to fit snugly but still avoid binding friction.
Hence, those concerned with the development and use of burning oil lamps in the field of esthetic illumination design have long recognized the need for an improved oil lamp structure which employs a larger oil vessel for providing a longer burning cycle, which can be inserted into the oil lamp through the lamp base notwithstanding the size of the chimney, which will be snugly secured to the lamp base yet be easily removed, which is comprised of materials which will not create intolerable binding friction, which is economical to produce over other lamp designs of the past, which exhibits simple lines and is esthetically pleasing, and the elements of which may be conveniently manipulated in position to accommodate packing and shipping.